package com.unit_7.util;

public class Vehicle {
    private double speed;
    public void start(){
        System.out.println("汽车启动！");
    }
    public void speedup(double speed){
        this.speed = speed;
        System.out.println("汽车加速到 " + speed + "km/h");
    }
    public void stop(){
        this.speed = 0;
        System.out.println("停车！");
    }
}
